Maybe you could call voters to action by saying we need to “protect our -lands-“ (stronger ring than air or water) or even better, “protect our -people- from having to live in a toxic environment”.
In my experience, conservatives care way more about the environment than anyone. They are the people who live, hunt, hike, farm, fish in the woods. The average conservative farmer/hillbilly has a much more personal connection with "the environment" than the average urban liberal.
But all things environment became associated with the left, so republicans have to reject it as a matter of course.
I think we need one good advertising campaign to seriously change people's minds. Something like, "Be a good steward of God's green earth". If we spoke their language, it would click.